The spring is heat sensitive. If the valve rotates freely in the manifold outlet and closes again when you let go, there is likely nothing wrong with it.
Bimetallic springs, ingenious things. You can test it with heat if you are curious. It will start to open with relatively low heat levels.
Ah! bimetal spring I never thought of that! It does rotate freely. So I guess it was working ok! Anyway I could feel the increased power as soon as I fired her up. My car also has duel exhausts all the way down. Am I right in saying the 326 250hp Firebird would have had a Y pipe making it a 2 into 1 system.
So I must have made quite a fifference to the power output by going 4bbl Edelbrock and duel plane Performer inlet and long headers with a duel exhaust.
I wanted to add cutouts for when I go drag racing but there was'nt enough straight exhaust pipe before in bends in and follows the prop and goes over that floor brace that the convertible has. I may tackle this later on and some straight through cherry bomb type exhaust on there. My next 2 major mods will have to be a higher stall TC and those 2.56 rear ends gears and open diff!
67 Firebird 350, TH350 auto Convertible, B&M 3000 TC, 4bbl Edelbrock Performer carb and intake Black Jack headers,disc brake conversion. 10 bolt chevy axle with 3.73's and B&M Rachet shifter.
